Method for reducing pressure losses in cyclone separator and ducting system for cyclone separator

ABSTRACT

A method for reducing pressure losses in a cyclone separator includes introducing a gas entraining a particulate material into a duct connected to the cyclone separator, separating at least a portion of the particulate material through an opening formed in a bottom surface of a horizontally extending section of the duct in proximity to a junction point of the duct to the cyclone separator, and introducing the gas entraining the particulate material into the cyclone separator. A ducting system for the cyclone separator includes the duct and the opening. The particulate material is prevented from being deposited and heaped in the vicinity of the junction point.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part application of applicationSer. No. 07/613,316 filed Nov. 8, 1990, now abandoned.

BACKGROUND OF THE INVENTION

This invention relates to a method for reducing pressure losses in acyclone separator and a ducting system by preventing a particulatematerial from being deposited and heaped in the vicinity of a junctionpoint between a duct and the cyclone separator to reduce pressure lossesin the cyclone separator.

A cyclone separator is a device well-known in the art as a dustcollecting system for separating and collecting a particulate materialfrom a gas entraining the particulate material under a centrifugalforce. With the cyclone separator, the gas is introduced into itsfunnel-shaped shell by means of a duct connected to the shell in atangential direction to impart a gyratory motion to the gas to separatethe particulate material from the gas.

The duct for introducing the gas into the cyclone separator has ahorizontally extending section in the vicinity of a junction point tothe funnel-shaped shell of the separator. The horizontally extendingsection is composed of a first horizontal portion having a width of theduct and a second horizontal portion extending narrowly from the firstportion and connecting with the funnel-shaped shell in a tangentialdirection thereof. It is at the first and second portions that theparticulate material tends to be deposited so as to disturb the flow ofthe introduced gas to thereby cause the increase of pressure losses inthe cyclone separator. In this case, a sufficient gyratory motion of thegas is not produced in the inside of the cyclone separator, such thatefficient separation of the particulate material from the gas cannot beachieved.

The conventional practice for preventing a particulate material frombeing deposited at the horizontally extending duct section has been toprovide the duct section with a tilt to cause the material to slidethereon to prevent its deposition. More specifically, the horizontallyextending duct section is inclined downwards towards its upstream sideor, alternatively, towards the funnel-shaped shell of the cycloneseparator. Still alternatively, the horizontally extending duct sectionhas a portion inclined downwards towards its upstream side and a portioninclined downwards towards the funnel-shaped shell of the cycloneseparator.

The above described conventional practice has, however, the followingdisadvantages. First of all, if the horizontally extending duct sectionis tilted downwards towards the upstream side of the duct, theparticulate material descending on the inclined portion is kept therestationarily by the entering gas stream, unless the tilt is steep tosome extent, with the result that the particulate material is depositedon the inclined duct section to disturb the introduced gas flow tothereby cause the increase of pressure losses in the cyclone separator.In addition, the particulate material continues to be deposited and,when reaching a certain amount or volume, the material can no longer bekept stationarily by the entering gas stream so that it collapsesintermittently and slides down along the inclined section towards theupstream side of the duct. This also causes a gas flow to be disturbed,leading to increased pressure losses in the cyclone separator. If thehorizontally extending duct section is inclined downwards towards thecyclone separator, the gas is introduced in the downward tangentialdirection into the inside of the shell of the cyclone separator so thatthe gas is directed towards a discharge duct provided at the bottom ofthe separator without a sufficient gyratory motion being imparted to thegas in the cyclone separator. As a result of insufficient separation ofthe gas and the particulate material in the shell of the cycloneseparator, the separation efficiency of the cyclone separator islowered. Finally, if the horizontally extending section has a portioninclined downwardly towards the upstream side of the duct and also aportion inclined downwardly towards the shell, the above describeddeficiencies are presented simultaneously. In addition, since theordinary duct annexed to the cyclone separator is extended horizontallyin the vicinity of the junction point to the shell, the remodellingconstruction work for imparting a tilt to the duct section istroublesome and also results in increased costs.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide a methodfor reducing pressure losses in a cyclone separator and stabilizing thecollection efficiency of the cyclone separator by preventing aparticulate material entrained in a gas from being deposited in ahorizontally extending section of a duct adapted for introducing the gasinto the cyclone separator and by allowing the gas to be introduced intothe separator without disturbing the gas flow and to provide a ductingsystem for the cyclone separator.

It is another object of the present invention to provide the abovemethod and system which permit the conventional ducting to be remodelledat lower costs.

The above and other objects of the present invention will becomeapparent from the following description.

For accomplishing the above objects, the present invention provides amethod for reducing pressure losses in a cyclone separator comprisingintroducing a gas entraining an entry particulate material into a ductconnected to the cyclone separator, separating at least a portion of theparticulate material through an opening formed in a bottom surface of ahorizontally extending section of the entry duct in proximity to ajunction point of the entry duct to the cyclone separator, andintroducing the gas entraining the particulate material into the cycloneseparator whereby the particulate material is prevented from beingdeposited and heaped in the vicinity of the junction point.

The present invention also provides a ducting system for a cycloneseparator comprising an entry duct for introducing a gas entraining aparticulate material into the cyclone separator and an opening formed ina bottom surface of a horizontally extending section of the entry ductin proximity to a junction point of the entry duct to the cycloneseparator, whereby at least a portion of the particulate material isseparated through the opening and the gas entraining the particulatematerial is introduced into the cyclone separator to prevent particulatematerial from being deposited and heaped in the vicinity of the junctionpoint to reduce pressure losses in the cyclone separator.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagrammatic front view showing an embodiment of a ductingsystem provided with an opening according to the present invention inconjunction with a funnel-shaped shell of a cyclone separator connectedto the ducting system.

FIG. 2 is a cross-sectional view taken along line II--II of FIG. 1.

FIG. 3 is a diagrammatic front view showing another embodiment of theducting system in conjunction with a funnel-shaped shell of a cycloneseparator.

FIG. 4 is a cross-sectional view similar to FIG. 2 showing a furtherembodiment of the ducting system provided with an opening different fromthe opening of FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIG. 1 of the accompanying drawings, the reference numeral1 denotes a cyclone separator provided with an entry duct 5 having aducting system or structure according to the present invention. Thecyclone separator 1 includes a funnel-shaped shell 3 for receiving adust-containing gas from the entry duct 5 and for separating the gasfrom the dust entrained therein, a discharge port 3a formed at thebottom of the shell 3 for discharging the dust separated from the gas inthe shell 3 out of the shell 3, a discharge duct 4 connected to thedischarge port 3a, and a gas discharge duct 2 for transporting theseparated gas towards an exterior device, not shown.

Still referring to FIG. 1 in conjunction with FIG. 2, the duct 5 iscomprised of an upstanding section 6 spaced from the cyclone separator 1and a horizontal section 7 extending horizontally from the upperterminal end of the upstanding section 6 and connected tangentially tothe shell 3. The horizontal section 7 is comprised of a first horizontalportion 7a having a width of the duct 5 and a second horizontal portion7b extending narrowly from the first portion 7a and connecting with theshell 3 in a tangential direction thereof, and the section 7 is providedwith an opening 8 having an area about equal to the area of the bottomsurface of the first horizontal portion 7a. To this opening 8 connectedis a hopper 9 having a triangular vertical cross section and arectangular horizontal cross section. As will be explained subsequently,the hopper 9 is comprised of a main hopper body 10 for collecting dustthat might otherwise be deposited in the portion 7a and a discharge pipe11 connected to a discharge opening formed in the bottom of the mainhopper body 10. The discharge pipe 11 is connected to the discharge duct4 at a sufficiently lower point thereof to prevent the flow of the dustback into the cyclone separator 1 by way of the discharge duct 4.

In FIGS. 1 and 2, the flow of the gas entraining the dust is indicatedby arrows for illustrating the function of the ducting system of thepresent invention. As shown in these figures, the gas entraining thedust, as indicated by an arrow A, ascends in the entry duct 5 from theupstream side of the upstanding section 6 so as to flow through thehorizontal section 7. During this time, a part of the dust entrained inthe gas as indicated by an arrow B is separated from the gas by its owngravity or by colliding against the upper surface of a transition zonebetween the section 6 and the portion 7a to descend into the hopper 9through the opening 8 so as to be discharged into the inside of thedischarge duct 4 of the cyclone separator 1 by way of the discharge pipe11 of the hopper 9. On the other hand, the gas flow entraining theremaining amount of the dust travels over the opening 8 as indicated byan arrow A' to proceed from the portion 7b into the inside of thecyclone separator 1 to perform a gyratory movement within the shell 3 ofthe cyclone separator 1. This gyratory movement of the gas, which iswell-known per se, is now explained only briefly. The gas performing thegyratory movement in the shell 3 descends gradually therein by itsgravity as it collides repeatedly against the wall surface of the shell3. At this time, the dust having a finer particle size is caused toascend by the gas stream in the cyclone separator 1 as indicated by anarrow C so as to be discharged towards an exterior equipment, not shown,via the gas discharge duct 2. Conversely, the dust of coarser particlesize continues to descend within the shell 3 as shown by an arrow D soas to be discharged through the discharge duct 4. The dust thusdischarged from the discharge duct 4 is united with the dust dischargedvia the discharge pipe 11 of the hopper 9.

FIGS. 3 and 4 each illustrates a modified embodiment of the presentinvention. In these figures, the same reference numerals are used todepict the same parts or components as those shown in FIGS. 1 and 2.

The embodiment shown in FIG. 3 mainly differs from the embodiment shownin FIG. 1 in that the discharge pipe 11' of the hopper 9 is notconnected to a downstream side point of the discharge duct 4 of thehopper 9, but is connected to the upstanding section 6 of the entry duct5 to return the dust collected by the hopper 9 into the entry duct 5 forpossible reutilization.

FIG. 4 shows an embodiment in which an area of the opening 8 isincreased by extending the opening 8 shown in FIG. 1 to the shell 3,that is, by extending the opening 8 to the second portion 7b. In thisembodiment, the opening 8 shown in FIG. 1 may be extended to the shell 3to a degree that the formula of at least a=L/3 is formed where L and aindicate the widths of the openings 8 at their ends in the vicinity ofthe shell 3 in FIGS. 1 and 4, respectively. According to the ductingsystem having the opening 8 in FIG. 4, the area on which the particulatematerial may be heaped and deposited is decreased as compared to theducting system shown in the embodiment of FIG. 1 so that the disturbanceof the gas flow in the separator 1 is reduced more effectively.

Although the present invention has been described with reference to thepreferred embodiments, it should be understood that variousmodifications and variations can be easily made by those skilled in theart without departing from the spirit of the invention. Accordingly, theforegoing disclosure should be interpreted as illustrative only and isnot to be interpreted in a limiting sense. The present invention islimited only by the scope of the following claims.

What is claimed is:
 1. A method for reducing pressure losses in acyclone separator comprising introducing a gas entraining a particulatematerial into an entry duct connected to the cyclone separator,separating at least a portion of said particulate material through anentry opening formed in a bottom surface of a horizontally extendingsection of said entry duct in proximity to a junction point of saidentry duct to the cyclone separator, and introducing the gas entrainingsaid particulate material into the cyclone separator, a hopper beingconnected to said entry opening and said portion of said particulatematering being discharged by way of a discharge opening of said hopper,said discharge opening of said hopper being connected to a dischargeduct of the cyclone separator for introducing said portion of saidparticulate material into said discharge duct, said horizontallyextending section comprising a first horizontal portion having a widthof said entry duct and a second horizontal portion extending narrowlyfrom the first portion and connecting with said separator in atangential direction thereof, said method further comprising separatingat least said portion of said material through said entry opening havingan area about equal to an area of a bottom surface of the first portionplus an area of a bottom surface of the second portion having at leastone-third width of said width of the entry duct whereby the particulatematerial is prevented from being deposited and heaped in proximity tosaid junction point.
 2. A ducting system for a cyclone separatorcomprising an entry duct for introducing a gas entraining a particulatematerial into the cyclone separator, an entry opening formed in a bottomsurface of a horizontally extending section of said entry duct inproximity to a junction point of said duct to the cyclone separator, anda hopper connected to said entry opening, an entry portion of theparticulate material being discharge by way of a discharge opening ofsaid hopper, said discharge opening of said hopper being connected to adischarge duct of said cyclone separator, said entry portion of theparticulate material being introduced into said discharge duct, saidhorizontally extending section comprising a first horizontal portionhaving a width of said entry duct and a second horizontal portionextending narrowly from the first portion and connecting with saidseparator in a tangential direction thereof, and said entry openinghaving an area about equal to an area of a bottom surface of the firstportion plus an area of a bottom surface of the second portion having atleast one-third the width of the entry duct, whereby at least an entryportion of said particulate material is separated through said entryopening and the gas entraining the particulate material is introducedinto the cyclone separator to prevent the particulate material frombeing deposited and heaped in proximity to said junction point to reducepressure losses in the cyclone separator.